Category Archives: Fish

Probably so. Mercury is the key pollutant people think about when considering polluted fish. Mercury toxicity isn’t on the list of top 10 killers in the U.S., but heart disease is.

Heart disease is #1 on the list of top causes of death, followed by cancer and chronic lower respiratory tract disease. “Heart disease” is a broad category; the primary killer is heart attacks. (Following heart disease as leading killer is cancer. Sadly, suicide is tenth leading cause of death. If you’re considering it, call the National Suicide Prevention Lifeline now.)

“Numerous studies have found that people who eat fish on a regular basis are less likely to die of a heart attack than those who don’t eat it or eat it less than once a month, and a 2006 Harvard review concluded that eating one to two servings of fish rich in omega-3s every week cut the risk of dying of a heart attack by one-third.”

Participants who ate seafood at least once a week had fewer Alzheimers lesions in their brains, but only if they were carriers of a particular gene the predisposes to Alzheimers. The gene is called apolipoprotein E or APOE ε4.

You’ve heard that seafood may be contaminated with mercury, right? The seafood eaters in this study indeed had higher brain levels of mercury, but it didn’t cause any visible brain damage.

The Mediterranean diet, relatively rich in seafood, has long been linked to a lower risk of dementia.

A weakness of the study is that the researchers didn’t report results of clinical testing for dementia in these participants before they died. You can have microscopic evidence of Alzheimers disease on a biopsy, yet no clinically diagnosis of dementia.

Fraudulent labeling of fish and other seafood is a problem. It matters to me because I advocate frequent consumption of cold-water fatty fish as healthful. It’s the omega-3 fatty acids in those fish that are good for you.

If what you believe to be trout is actually catfish, you’re not getting the omega-3s you paid for.

Click over to the New York Times for details:

“One in five seafood samples tested worldwide turns out to be completely different from what the menu or packaging says, according to a report on seafood fraud released Wednesday by the ocean conservation group Oceana. Of the more than 25,000 seafood samples the group analyzed, 20 percent were incorrectly labeled.“It is likely that the average consumer has eaten mislabeled fish for sure,” said Beth Lowell, the senior campaign director for Oceana and an author of the paper. “You’re getting ripped off, while you enjoyed your meal you’re paying a high price for a low fish.”

On a related note…I’ve been eating a lot of canned smoked oysters lately. Nearly all on the supermarket shelves in Arizona USA come from China. Why is that? I worry about pollutants in those oysters, regardless of provenance. If you have any info on this issue, please share.

Several years ago, Alton Brown lost a significant amount of weight, and one of the items on his diet was sardine-avocado sandwiches. I like sardines. I like avocados. But I never ever would have considered eating them mixed together.

A while back, I read Franziska Spritzler’s The Low Carb Dietitian’s Guide to Health and Beauty (great book; my review). One of her recipes involves the sardine-avocado combo, so I’m resolved to give it a try. Her recipe was simply 4 oz (120 g) canned sardines mixed with 1/2 medium avocado and sea salt, stuffed in a large red bell pepper. I bet the sardine-avocado mix would be good on a bed of lettuce if I don’t have a bell pepper. A little black pepper and a squeeze of lemon, too?

If memory serves, I paid $1.29 (USD) for this tin of sardines. “Best used by” date is five years from now.

I may even try Franziska’s Chocolate Avocado Pudding, another combo I never would have imagined.

The Environmental Working Group published an article reviewing the risk of mercury poisoning from seafood consumption. I’m not familiar with EWG. I’m trying not to hold it against them that Dr. Mark Hyman is on the board of directors.

Anyway, the EWG has some advice for you if you worry about mercury toxicity from fish. I try to stay up to date on the issue since I’m convinced that consumption of cold-water fatty fish twice a week is good for your health, in general. If the mercury doesn’t kill you. Seafood is key component of the Ketogenic Mediterranean Diet, the foundation of the Low-Carb Mediterranean Diet.

Here are some quotes from the EWG article:

…EWG has compiled a list of “moderate mercury” species that would pose a mercury risk for pregnant woman and children who eat fish regularly. This list is more comprehensive than the 2004 EPA/FDA advisory, which warned that women of childbearing age and young children, who are most susceptible to the damage done by mercury, should eat only six ounces a week of albacore tuna and should avoid four other high-mercury species – swordfish, tilefish, king mackerel and shark.

EWG rightly points out that much of the “seafood” consumed in the U.S. really doesn’t provide much of the healthful omega-3 fatty acids.

Among popular seafood species, salmon stands out as an excellent choice. Four to eight ounces of salmon weekly, depending on the species, can provide 100 percent of the recommended amount of omega-3s. Some types of farmed salmon present significant environmental health concerns. EWG recommends that people choose wild salmon instead.

EWG’s analysis highlights several other affordable and sustainably produced species, including anchovies, sardines, farmed trout, and mussels. Just four to eight ounces of these species weekly would meet recommended omega-3 requirements for pregnant women and people with heart disease.

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Americans eat more than 400 million pounds of canned imported tuna because it is affordable and can be stored for a long time. Canned tuna is the second most popular seafood in the U.S., after shrimp. An average American eats an average of 2.5 pounds of tuna every year (NOAA 2012). Albacore tuna, also called “white” tuna, contains significant amounts of omega-3s, but tests indicate that it also contains significant amounts of mercury. “Light” tuna is usually skipjack tuna but can also contain yellowfin tuna. Skipjack and yellowfin have lower mercury levels than albacore, but fewer omega-3s.

As Jim Gaffigan asked, “Has anyone even bothered to ask why the tuna are eating mercury?”

In 30 years of practicing medicine, including 12 years right on the Gulf Coast, I’ve never seen a case of mercury toxicity. Maybe I’ve missed it. Maybe it’s quite rare.

Salmon is one the the cold-water fatty fish loaded with omega-3 fatty acids

I’ve been sitting on this research report a few years, waiting until I had time to dig into it. That time never came. The full report is free online (thanks, British Medical Journal!). I scanned the full paper to learn that nearly all the studies in this meta-analysis used fish oil supplements, not the cold-water fatty fish the I recommend my patients eat twice a week.

Here’s the abstract:

Objective: To review systematically the evidence for an effect of long chain and shorter chain omega 3 fatty acids on total mortality, cardiovascular events, and cancer.

Review methods Review of RCTs of omega 3 intake for 3 6 months in adults (with or without risk factors for cardiovascular disease) with data on a relevant outcome. Cohort studies that estimated omega 3 intake and related this to clinical outcome during at least 6 months were also included. Application of inclusion criteria, data extraction, and quality assessments were performed independently in duplicate.

Results: Of 15 159 titles and abstracts assessed, 48 RCTs (36 913 participants) and 41 cohort studies were analysed. The trial results were inconsistent. The pooled estimate showed no strong evidence of reduced risk of total mortality (relative risk 0.87, 95% confidence interval 0.73 to 1.03) or combined cardiovascular events (0.95, 0.82 to 1.12) in participants taking additional omega 3 fats. The few studies at low risk of bias were more consistent, but they showed no effect of omega 3 on total mortality (0.98, 0.70 to 1.36) or cardiovascular events (1.09, 0.87 to 1.37). When data from the subgroup of studies of long chain omega 3 fats were analysed separately, total mortality (0.86, 0.70 to 1.04; 138 events) and cardiovascular events (0.93, 0.79 to 1.11) were not clearly reduced. Neither RCTs nor cohort studies suggested increased risk of cancer with a higher intake of omega 3 (trials: 1.07, 0.88 to 1.30; cohort studies: 1.02, 0.87 to 1.19), but clinically important harm could not be excluded.

Conclusion: Long chain and shorter chain omega 3 fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer.

Now, consider the possibility that we weren’t meant to burn glucose at all as a primary fuel. Consider the possibility that fat was meant to be our primary fuel. In my current state of dietary practice, I am burning fat as my main source of energy. My liver is converting some of it to ketones which are needed to fuel the majority of my brain cells. A small fraction of the brain cells, around 15%, need glucose along with a few other tissues like the renal cortex, the lens of the eye, red blood cells and sperm.Their needs are met by glucose that my liver produces from proteins. The rest of my energy needs are met with fatty acids and these come from the fats I eat.

Dr. Wortman, who has type 2 diabetes, in the same long post also writes about oolichan grease (from fish), an ancestral food of Canandian west coast First Nations people.